Hey guys. I got my Samsung 840 EVO 250GB just 5 days ago and I'm using Samsung Magician to monitor how much data has been written to it. When I reformatted my PC with the new drive, Magician says 0.04TB (that's 40GB) has been written. Fair enough, since I installed WIndows 7 x64, AMD Chipset drivers, HD7770 drivers, Realtek LAN controller drivers, Sound Blaster X-Fi drivers and Creative Console, Wi-Fi adapter drivers... the usual stuff. Then I proceeded to install MS Office 2007, GIMP, Foxit Reader, Firefox, Avast Free Antivirus, CDBurnerXP, CCleaner and a few small apps more.

Now my concern is that Magician is saying that something like 0.01TB is being written everyday. Total written data now stands at 0.08TB after just 5 days of use and I don't think there's any way I am managing to write 10GB of data on this thing every day. Early on I already disabled System Restore, Windows Update, and indexing service for both the EVO and my 1TB Hitachi HDD, and later on also disabled hibernation as well as configured the page file to use the Hitachi HDD. Firefox is set to have 128MB of cache but it can't possibly be caching 10GB a day. I installed a few games since getting this HDD but it also couldn't have been 10GB a day. Is Samsung Magician being too quick in counting the bytes or could there be something strange going on? Are you guys exhibiting this much written data? At 0.01TB a day, it would be 3.65TB a year. Is this right? Right now I'm using just 9.6% of the 250GB.

If people stick with you just because you have a Rolex on your wrist, you can bet losing them is as OK as losing an Invicta. And if they stick with you even if you only have an Invicta, losing them is as OK as losing a Rolex.

Did you also let Magician disable Prefetch and Superfetch? I don't think 0.08TB is cause for panic just yet. You've got a fresh install of Windows and you're still installing stuff. I'd wait until after things have settled down a bit and see what happens. It could also be something like CCleaner constantly wiping all your cache files (only to have them rewritten the next time you use the program). I personally don't like those stupid "cleaner" utilities. Anything that mentions the windows registry is a snake oil program. I don't think I've seen a "registry error" since Windows 95.

IIRC, Intel says a typical consumer SSD workload is about 10 gigabytes per day, but I can't find a source for that right now, so feel free to not believe it. Regardless, I don't think .01TB a day of writes is anything to worry about. 3.65TB a year for 50 years will still be under 200TB, and the standard 840 TR has been abusing in the SSD endurance experiment was still working more or less fine at that point.

Edit: Intel rates their SSDs based on "typical client workloads with up to 20 GB of host writes per day". I found this in the data sheets for a bunch of their SSDs in the "reliability" section. For example: Intel 320 Series data sheet (pdf)

I know you don't have an Intel SSD, I'm just mentioning this as an example of how much data SSD makers expect to be written to their devices.

The Egg wrote:Did you also let Magician disable Prefetch and Superfetch? I don't think 0.08TB is cause for panic just yet. You've got a fresh install of Windows and you're still installing stuff. I'd wait until after things have settled down a bit and see what happens. It could also be something like CCleaner constantly wiping all your cache files (only to have them rewritten the next time you use the program). I personally don't like those stupid "cleaner" utilities. Anything that mentions the windows registry is a snake oil program. I don't think I've seen a "registry error" since Windows 95.

Nope, Prefetch and Superfetch are not disabled. But I would think those features mainly read from, not write to, the SSD. As for installing stuff, I install old games, and since starting to use the SSD and initially having written 0.04TB, I installed, what, maybe 1 to 2GB worth of stuff. Pretty much not installing anything new now. As for Ccleaner, I don't run it all the time, and if I do, most of the things it wipes away are from the Firefox internet cache, which is set to 128MB max.

If people stick with you just because you have a Rolex on your wrist, you can bet losing them is as OK as losing an Invicta. And if they stick with you even if you only have an Invicta, losing them is as OK as losing a Rolex.

Swap file + write amplificaton = lots of writes. AFAIK the block size on Samsung's 19NM TLC is 2MB, so the tiniest write you make always ends up writing at least 2MB to the drive. This includes firefox's cache. Those 1kb transparent gifs will be causing 2MB writes every time unless you somehow consolidate those writes.

Have you tried turning on RAPID? It should decrease the number of writes to SSD because you'll use system RAM as a cache first.

Keep in mind that any time you touch a file there's also filesystem meta-data that needs to be updated; and writes always occur in sector-size chunks, even if only a single byte is being changed. Furthermore, even after disabling all the stuff you've disabled, Windows is still doing a lot of stuff in the background. Ever notice how the HDD activity light keeps blinking intermittently, even on an "idle" Windows system?

To (hopefully) put things in perspective, 10GB is only about 20 seconds worth of sustained writes.

And then there's the potential write amplification issue jihadjoe mentioned. I'm not sure whether Magician is tracking host (OS) write requests, or actual, physical writes to the flash array. If it is the latter, then 10GB actually seems a little low to me!

The years just pass like trains. I wave, but they don't slow down.-- Steven Wilson

Hmm... so even if I write just a few hundred kilobytes, the SSD writes an entire 2MB block? Unless I'm writing data that's large enough to fill entire 2MB blocks and not waste much of a 2MB write, I'll end up using my 'write headroom' far more quickly, wouldn't I? Is this right? A bit worrying even if I compare this to TR's SSD endurance tests. Of course even if I write twice or trice that amount (0.03TB) it would still take me 27 years to render this drive useless, assuming it has a limit of 300TB writes.

If people stick with you just because you have a Rolex on your wrist, you can bet losing them is as OK as losing an Invicta. And if they stick with you even if you only have an Invicta, losing them is as OK as losing a Rolex.

Microsoft wrote:In looking at telemetry data from thousands of traces and focusing on pagefile reads and writes, we find that•Pagefile.sys reads outnumber pagefile.sys writes by about 40 to 1, •Pagefile.sys read sizes are typically quite small, with 67% less than or equal to 4 KB, and 88% less than 16 KB.•Pagefile.sys writes are relatively large, with 62% greater than or equal to 128 KB and 45% being exactly 1 MB in size.

"Welcome back my friends to the show that never ends. We're so glad you could attend. Come inside! Come inside!"

ronch wrote:Hmm... so even if I write just a few hundred kilobytes, the SSD writes an entire 2MB block? Unless I'm writing data that's large enough to fill entire 2MB blocks and not waste much of a 2MB write, I'll end up using my 'write headroom' far more quickly, wouldn't I? Is this right?

I don't think that's correct. My understanding is that each byte can be written individually (although the filesystem probably requires an entire allocation unit to be written at once), but it can only be erased an entire block at a time. Once enough of the block is either out of date or trimmed, the remaining current data will be written to a different block so the first block can be erased and reused.

just brew it! wrote:SATA protocol is inherently sector-based; there isn't a "modify one byte in a specified sector" command. Flash also cannot rewrite an individual byte in place; the sector must be erased first.

So if a block is erased, then one sector in that block is written, does the entire block have to be erased again to write to a different sector that hadn't been written to since the first erase?

NAND flash is organized into blocks, which are subdivided into pages, which are further subdivided into sectors. Erasures must be done on a block basis; writing is done on a page basis, or (via a feature called "partial page programming") can be done on a sector basis in certain situations.

Erasing a block sets all of the bits in the block to '1'. Writing can only change the state of bits from '1' to '0'. This is why blocks need to be erased before any of the pages can be re-used.

All of this is completely hidden by the flash controller in the SSD. In some cases (e.g. SandForce) there isn't even a 1-to-1 correspondence between sectors that are visible to the OS and sectors on the NAND flash chips, since the controller does on-the-fly data compression to minimize write amplification.

The years just pass like trains. I wave, but they don't slow down.-- Steven Wilson

just brew it! wrote:As noted above, I am not sure whether Magician is measuring the amount of data written by the host, or the amount of data written to the flash array (after write amplification).

According to Samsung, the 0xF1 or 241st attribute in SMART of the 830/840 series stores the amount of sectors the SSD had to erase in order to perform the requests sent by the OS. This SMART attribute is exactly what SSD Magician shows in its GUI.

Represents the total size of all LBAs (Logical Block Address) required for all of the write requests sent to the SSD from the OS. To calculate the total size (in Bytes), multiply the raw value of this attribute by 512B. Alternatively, users may simply consult the Total Bytes Written indicator in Magician 4.0.

And, unfortunately, SSD's cannot erase... Wait, this story about pages and problems with writing ones has already been posted in the mean time. Thanks brewer.

So, the dreadful version of the story is that you're writing in 2MiB pieces. So, if you add and save a few character inside a text file, you're writing these changes (2MiB), the file timestamp in the $MFT gets updated (2MiB), the list of free sectors on the drive storedin $Bitmap might change (2MiB), and for the fun of it your file might be part of some system restore plan in which case various files in System Volume Information get updated (2MiB).

just brew it! wrote:As noted above, I am not sure whether Magician is measuring the amount of data written by the host, or the amount of data written to the flash array (after write amplification).

According to Samsung, the 0xF1 or 241st attribute in SMART of the 830/840 series stores the amount of sectors the SSD had to erase in order to perform the requests sent by the OS. This SMART attribute is exactly what SSD Magician shows in its GUI.

Represents the total size of all LBAs (Logical Block Address) required for all of the write requests sent to the SSD from the OS. To calculate the total size (in Bytes), multiply the raw value of this attribute by 512B. Alternatively, users may simply consult the Total Bytes Written indicator in Magician 4.0.

And, unfortunately, SSD's cannot erase... Wait, this story about pages and problems with writing ones has already been posted in the mean time.

OK, based on this, it sounds like the counter is simply the number of 512 byte sectors the host has sent to the drive. In other words, it does not take write amplification, compression, or garbage collection into account.

The years just pass like trains. I wave, but they don't slow down.-- Steven Wilson

morphine wrote:Let's just keep this in perspective - like Geoff has proven, it takes a LOT of terabytes to kill an SSD.

On average perhaps but a failure can happen at anytime and just because Geoffs specific drives don't experience a failure doesn't mean someone else won't. The problem with Geoff's test is that it has a very small sample size.

morphine wrote:Let's just keep this in perspective - like Geoff has proven, it takes a LOT of terabytes to kill an SSD.

Their tests involve writing huge amounts of data that fill whole blocks, so every byte counted was actually useful data. But in typical client workloads, if writing just a few KB results in writing whole blocks thereby 'wasting' most of a block write, the amount of useful data that you actually write dramatically shrinks, doesn't it? So when Magician says I already wrote 80GB, while it may be true that 80GB was actually written, it was only because of the way the drive works internally and I and my apps actually wrote far less than that.

If people stick with you just because you have a Rolex on your wrist, you can bet losing them is as OK as losing an Invicta. And if they stick with you even if you only have an Invicta, losing them is as OK as losing a Rolex.

Even if the .01TB/day rate is sustained indefinitely, you're likely looking at several *decades* before the drive dies due to flash wear. Stop worrying and enjoy the improved system performance from your new SSD.

The years just pass like trains. I wave, but they don't slow down.-- Steven Wilson